First, right-click on the files you want to open in the new version of the software, click Properties, select the General tab and check the information next to Type of file. If it is a .cdo file, try to download and install the software again. If it still doesn't work, use the contact information from the official web page to get in touch with the developers. Also, you can try exporting your work as a .mid file (File > Export MIDI) and importing it in the new version of the application.